'use strict'

const http = require('http')
const fs = require('fs')
const { brotliDecompress } = require('zlib')

function parseBodyHeaders(data){
    let headers = {}
    let dsplit = data.split('\r\n').filter(p => p.length > 0)

    let ind
    let k
    for(let d of dsplit){
        ind = d.indexOf(':')

        if(ind <= 0) continue

        k = d.substring(0, ind).toLowerCase()

        headers[k] = d.substring(ind+1).trim()
    }

    let cpd = headers['content-disposition']

    //按照;分割成数组，第一个元素form-data去掉
    let clist = cpd.split('; ').slice(1)

    let name, filename

    for(let a of clist){
        ind = a.indexOf('filename="')
        if(ind >= 0){
            filename = a.substring(ind+10, a.length-1)
        }else{
            name = a.substring(6, a.length-1)
        }
    }

    return{
        headers,
        name,
        filename
    }
}

/**
 * 
 * @param {Buffer} bodyData 原始的Body数据
 * @param {Object} reqHeaders request.headers
 */

function parseBody(bodyData, reqHeaders){

    //content-type: multipart/form-data; boundary=-----34294329
    let ctype = reqHeaders['content-type']

    //拿到分界线的boundary
    let bdy = ctype.substring(ctype.indexOf('=')+1)

    //数据中用于分割文件的分界线
    // bdy = `--${bdy}\r\n`

    let crlf_bdy = `\r\n--${bdy}`

    //从偏移bdy的长度开始查找下一个分界线的位置
    let data_end_index = bodyData.indexOf(crlf_bdy, crlf_bdy.length)

    //body消息数据中header部分最后的索引
    let header_end_index = bodyData.indexOf('\r\n\r\n', crlf_bdy.length)

    let header_data = bodyData.toString('utf8', crlf_bdy.length, header_end_index)

    //解析body数据中的消息头
    let hd = parseBodyHeaders(header_data)

    let fileinfo = {
        start: header_end_index+4,
        end: data_end_index,
    }
    fileinfo.length = fileinfo.end - fileinfo.start

    return{
        name: hd.name,
        filename: hd.filename,
        headers: hd.headers,
        start: fileinfo.start,
        end: fileinfo.end,
        length: fileinfo.length
    }
}

let routerTable = {

GET:{
    '/upload':async(request, response) => {
        let stm = fs.createReadStream('./upload.html')
        stm.pipe(response)
        stm.on('end', ()=>{
            response.end()
        })
    }
},

POST:{
    '/upload':async(request, response) => {

        console.log(request.headers['content-type'])

        let bufferList = []
        let totalLength = 0

        request.on('data', chunk => {
            totalLength += chunk.length
            bufferList.push(chunk)
        })

        let bodyData = null

        request.on('end', () => {
            bodyData = Buffer.concat(bufferList, totalLength)
            bufferList = []

            //解析Body数据
            let body = parseBody(bodyData, request.headers)
            console.log(body)

            response.setHeader('content-typr', 'text/plain; charset=utf-8')
            response.end(bodyData)
        })
    }
}

}

let serv = http.createServer()

serv.on('request', (request, response) => {
    let rm = routerTable[request.method]

    //根据？切分字符串
    let usplit = request.url.split('?')

    let pathname = usplit[0]
    let querystring = usplit[1] || ''

    if(!rm || !rm[pathname]){
        response.statusCode = 404
        response.end('page not found')
        return
    }

    rm[pathname](request, response)
})

serv.listen(3456)